Clinicopathological and prognostic relevance of EZH2 expression in renal cell carcinoma: a meta-analysis

Background: The prognostic value of zeste homolog 2 (EZH2) in renal cell carcinoma (RCC) has been reported in a large number of studies. However, the results from these studies are inconsistent and remain in conclusive. We conducted a systematic review and meta-analysis to explore the significance of EZH2 expression in patients with RCC. Methods: We searched PubMed, Embase, ISI Web of Knowledge and Cochrane Library to identify studies written in English. The methodological quality of the studies was also evaluated. Odds ratio (OR) and hazard ratio (HR) were calculated and summarized. Results: Eleven eligible studies including 2305 RCC patients were identified. We observed that EZH2 expression was significantly higher in the RCC tissue than the normal renal tissue (OR: 7.88, 95% CI 4.33-14.36, P < 0.00001). EZH2 expression was not associated with tumor type or sex (OR: 0.73, 95% CI 0.46-1.15, P = 0.18; OR: 1.20, 95% CI 0.94-1.52, P = 0.14). However, EZH2 expression was clearly associated with clinical staging (OR: 0.44, 95% CI 0.34-0.55, P < 0.00001), Fuhrman grading (OR: 0.55, 95% CI 0.42-0.72, P < 0.0001) and metastatic status (OR = 0.45, 95% CI 0.34-0.60, P < 0.00001). A statistically significant combined HR was detected for overall survival (OR: 2.85, 95% CI 2.05-3.98, P < 0.00001), progression-free survival (OR: 3.09, 95% CI 1.49-6.43, P = 0.002), and disease-free survival (OR: 2.69, 95% CI 1.74-4.17, P < 0.00001). The results of this meta-analysis suggest that EZH2 expression is associated with an increased risk of RCC and worsened survival of RCC patients. Aberrant EZH2 expression plays an important role in the carcinogenesis and prognosis of RCC.